SPECIFICATION FOR EARTH WORK AND SUB-GRADE PREPARATION

SPECIFICATION FOR EARTH WORK AND SUB-GRADE PREPARATION

 

1.0 SCOPE

 

This specification covers the materials and construction for site preparation, earthwork, general grading, and site drainage for the Rajasthan Northern Area Development.

2.0 CODES, REGULATIONS  AND STANDARDS  

General

CONTRACTOR shall meet or exceed the requirements of the latest edition of the following codes, regulations and standards, except as superseded herein. In cases where more than one code, regulation or standard apply to the same condition, the most stringent shall be followed. In the event of a conflict between this specification and other specifications or correspondence, the COMPANY shall be consulted and a ruling, in writing, shall be obtained before any work is started.

 

2.1.1    International Standards

 

a.      ASTM D698               Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort

b.      OSHA 29 CFR 1926, Subpart P, "Excavations"

 

2.1.2    Indian Standards

          a.      IS 2720

 

b.      IS 3764

Methods of test for soils

 

Code of Safety for Excavation Work.

 

2.1.3    The following general specifications and documents shall be used in conjunction with this specification where applicable:

 Road Works

 

Road Drainage

 

Underground Services Construction

 

Report No.FGTL/191/06            Geotechnical services for Rajasthan Northern Area Development                                     -Mangala Process Terminal, by Fugro-India.

 

Report No. FGTL/191/06

 

 

Report No. FGTL/191/06

Geo technical Services for Rajasthan Northern Area Development-Oil Well Pads and Operations Base (Living Quarters) by Fugro-India

 

Geotechnical Services for Rajasthan Northern Area Development-

Thumbli Water Field by Fugro-India

 

IS 10379: Code of practice for field control of moisture Compaction of soils for embankment and

 

MORT & H

2.1.4    Other

 

a.       Codes, Regulations and Statutes of Authorities having jurisdiction in location of installation.

 

b.       National Building Code Of India

 

2.1.5    Some requirements in this specification may be modified by specific requirements in the project. In case of conflict, the order of precedence will be the specific requirements in the Project.

 

3.0 GENERAL 3.1         Workmanship

Work shall be carried out in accordance with code requirements and industry standards for good workmanship.

3.2    CONTRACTOR’S Design Data

 

Upon completion of project CONTRACTOR shall supply COMPANY with one copy of all drawings marked with "As-Built" information.

3.3    Definitions

 

COMPANY:    The COMPANY means Cairn Energy Pty Limited, and its subsidiaries or authorized representatives.

CONTRACTOR: Person(s), company, firm, manufacturers, fabricator or vendor.

4.0 MATERIALS AND COMPACTION 4.1    Material Substitution

No material other than that specified shall be used unless accepted, in writing, by COMPANY. 4.2         Site work Definitions

4.2.1    Top soil is defined as humus, peat and similar decomposed organic material making up the top layer of the soil and suitable for supporting the growth of vegetation.

 

4.2.2    Excavation material is defined as all material such as top soil, earth, muck, clay, soft shale, sand, gravel and any such material which can be removed without drilling and blasting.

4.2.3    Rock excavation material is defined as material being of sufficient hardness as to require drilling, blasting or breaking with a power operated hand tool to facilitate its removal and shall include solid ledge rock and detached masses of rock or concrete exceeding 1.0 m3 in volume, but shall not include soft or disintegrated rock which can be broken with a hand pick or power operated excavator, ripper or shovel; hardpan; previously blasted or broken stone in rockfills or elsewhere which is less than 1.0 m3 in volume; and boulders or pieces of fragmented rock which do not occur naturally within the excavated volume but fall into the excavation from an adjacent area.

 

4.2.4    Borrow material is defined as all suitable material obtained from borrow areas on or off the job site. Material shall be borrowed from locations approved by the COMPANY.

4.2.5    Fill material is defined in paragraph 4.3 and shall be free from all roots and organic matter, frozen lumps, rocks greater than 150 mm in diameter.

4.2.6    Rip-rap for slope protection shall be formed from field stone or rough surface quarry stone conforming to the following gradation:

 

 

Stone Weight	Approximate Size	Percent Larger Than
50 kg	300 mm	0 – 10
20 kg	225 mm	25 - 75
6 kg	150 mm	90 - 100

4.3    Fill Material

 

4.3.1    Excavated Sand (Onsite sand) Fill

 

4.3.1.1 Excavated on-site soil can be used as fill material.

 

4.3.2     Crushed Stone Fill

 

4.3.2.1 Crushed stone fill material shall be well graded angular crunched stones having particle size of less than 3.8 cm and no more than 10 percent material passing the No. 200 sieve.

 

4.3.2.2 All crushed stone material shall be approved for use by the COMPANY

4.4    Gravel Pad

 

4.4.1    Crushed stone may be used for the Gravel Pad. The crushed stone shall be placed in loose lifts not more than 15 to 20 cm thick and uniformly compacted to 98 percent of the maximum dry density at a moisture content within 1 percent dry to 3 percent wet of the optimum moisture content as determined by ASTM D698.

4.5    Crushed Gravel Surfacing

 

4.5.1    Crushed gravel shall be free of any form of coating, clay, shale, silt, friable materials, loam, or other deleterious materials and shall be non-frost susceptible.

 

4.5.2    Crushed gravel surfacing material shall be placed and spread evenly over the designated areas. This material shall be thoroughly compacted using a mechanical tamper or lightly rolled using a vibratory roller.

 

4.5.3    Crushed gravel shall conform to the following gradations unless approved by the COMPANY:

 

Size Range	IS Sieve Designation	Per cent by weight passing
63 mm to 45 mm	90 mm	100
	63 mm	90-100
	53 mm	25-75
	45 mm	0-15
	22.4 mm	0-5

 

4.6    Compaction of Fill Material

 

4.6.1    Onsite excavated sand shall be placed in loose lifts not exceeding 15 to 20 cm at a moisture content within 2 percent of the optimum moisture content and compacted to at least 95% of maximum dry density as determined by ASTM D-698 using a (90 KN) vibratory roller.

4.6.2    Potable water is generally considered satisfactory for use in soil moisture adjustment. The PH value of water must be not less than 6.

4.7     Compaction of Crushed Stone Fill

 

4.7.1    The crushed stone fill or backfill material shall be placed in loose lifts no more than 15 to 20 cm thick and uniformly compacted to 98 percent of the maximum dry density.

 

4.7.2    Moisture content for the crushed stone material shall be within 1 percent dry to 3 percent wet of the optimum moisture content as determined by ASTM D-698.

5.0 EARTHWORK AND GENERAL GRADING 5.1         Work Involved

Earthwork and general grading may include the following work: clearing, grubbing, stripping, excavation, fill, compaction, disposal of surplus material, borrowing of suitable material, related survey work for layout of the work on site, construction of site roads, site drainage, bases and dikes for storage tanks, and upkeep and dust control of the gravel access road leading to the plant site.

5.2    General

 

5.2.1    Surveying

 

CONTRACTOR shall be responsible for all detailed layout to ensure that the works are constructed as shown on the drawings. COMPANY reserves the right to check and confirm any layout performed by the CONTRACTOR.

5.2.2    Dewatering

 

a.      CONTRACTOR shall keep all excavations, pits and the entire Subgrade free of water at all times during the course of the work and all necessary pumps or other suitable equipment, and any necessary temporary drainage system, shall be provided to meet this requirement.

 

b.      CONTRACTOR shall use extreme caution in positioning pumps, well points or other dewatering equipment, and the discharge from same, to ensure that damage does not occur to existing structures and to works under construction.

 

c.      It shall be the responsibility of CONTRACTOR to determine the amount of water to be encountered and to include the cost of handling this water. Any additional excavation made necessary by water in the excavation shall be considered as unauthorized over-excavation.

5.2.3    Locations and Protection of Existing Structures

 

a.      Existing structures are defined as all existing pipes, ducts, manholes, ditches, culverts, septic tanks, water wells or other works forming a part of sewage, drainage, water, telephone, electrical, gas or other utility systems as well as sidewalks, roadways, poles, fences, buildings and their foundations, equipment and associated piping and other man    made items that may be encountered.

 

b.      CONTRACTOR shall be responsible for locating existing surface and underground structures; all drawings or descriptions of existing structures or their locations that are given to CONTRACTOR are intended only as an aid to its location of these structures.

 

c.      CONTRACTOR shall protect all existing structures, both surface and underground, from:

 

           Damage during construction, except where demolition of specified existing structures is included in the Work or specific authorization for their removal is received, in writing, from COMPANY.

 

d.      All existing underground structures which are to be protected from damage shall be located by hand digging or water jet.

 

e.      CONTRACTOR shall repair or replace, at his own expense, any existing structure which is damaged during construction. Such repair or replacement shall be to COMPANY's satisfaction and a condition which is at least the equivalent of that which existed prior to construction.

5.2.4    Underground Utilities

a.      Protect active utility lines or electrical conduits shown on the drawings unless shown to be removed or otherwise made known to the CONTRACTOR prior to excavating. If damaged, repair or replace at no additional cost to the COMPANY.

b.      If active utilities are encountered that are not shown on the drawings or otherwise made known to the CONTRACTOR, promptly take necessary steps to assure that the utility service is not interrupted.

c.      If service is interrupted as a result of work under this section, immediately restore service by repairing the damaged utility at no additional cost to the COMPANY.

d.      If existing utilities are found to interfere with the permanent facilities being constructed under this section, immediately notify the COMPANY’s representative for instructions.

e.      Do not proceed with permanent relocation of utilities without written instructions from the COMPANY.

 

5.2.5    Protection of Persons and Property

a.      Strictly adhere to OSHA and Client safety standards at all times.

 

b.      Barricade open holes and depressions occurring as part of the work. Post appropriate warning signs.

c.      Protect structures, utilities, sidewalks, pavements and other facilities from damage caused by settlement, lateral movement, washout or other hazards created by operations under this specification.

 

d.      Where excavation is done near existing work, take care not to undermine or weaken the foundation or soil support of such work. Install underpinning or shoring where necessary. Such shoring, including sheet piling, shall be properly engineered and installed.

 

5.2.6    Seal Slab (Lean-mix Concrete Slab)

 

5.2.6.1 A thin un-reinforced concrete seal slab may be provided directly below the bottom of a foundation to facilitate construction operations. This slab shall not be considered as part of the foundation.

5.2.7    Controlling Dust

 

5.2.7.1          Prevent dust from becoming a nuisance to adjacent plant operations.

5.2.8    Adjacent Plant Access

 

5.2.8.1 Plan earth moving operations so as to maintain access to adjacent plant operations areas at all times.

5.3    Clearing

 

5.3.1    CONTRACTOR shall clear the areas within the limits designated on the drawings by removing all trees, bushes, dense growth or ground plants and other vegetation, alive or dead to natural grade where possible. Clearing shall also include the removal of dense growths of ground plants, matted dead vegetation and rubbish resting on natural grade. Trees up to 300-mm girth shall be uprooted. Trees

above 300 mm girth shall be cut. Remaining stump and root system shall be marked by the CONTRACTOR for later removal.

 

5.3.2    Where selective clearing is required CONTRACTOR shall protect and preserve all trees or groups of trees selected for preservation as designated on the drawings or by COMPANY in the field. CONTRACTOR shall salvage all timber as required by local Forestry representatives.

5.3.3    Clearing shall also include the removal of any existing structures, foundations, buried piping and conduit as directed by COMPANY.

5.3.4    CONTRACTOR shall dispose of all clearing materials in accordance with all Municipal, Provincial or Central Government regulations, by burning or otherwise, on site or elsewhere and as approved by COMPANY and shall obtain all required burning and disposal permits.

5.4    Stripping and Grubbing

 

5.4.1    CONTRACTOR shall strip and grub the site within the limits designated on the drawings by removing all tree stumps and other plant life, including all root structures, trash, loose stones, top soil and organic materials to the depth indicated on the drawings or as directed by the COMPANY.

5.4.2    CONTRACTOR shall backfill excavations or cavities resulting from the removal of tree trunks, roots or other material, as part of the grubbing operation.

5.4.3     CONTRACTOR shall obtain all required disposal permits and dispose of all stripping and grubbing materials in accordance with all Municipal, Estate or National regulations. All disposals, on site or elsewhere, shall be as directed by the COMPANY.

 

5.5    Excavation

 

5.5.1    Excavation shall include the removal and transportation of all excavated materials whether wet or dry, from the point of excavation to the point of final use or disposal. It shall also include the disposal of all unsuitable and surplus materials.

 

5.5.2    Excavated materials that are unsuitable for or in excess of backfill shall be wasted in disposal areas as directed by the COMPANY.

 

5.5.3    Excavation and general grading shall conform to the lines, elevations and grades shown on the drawings. Rough grade shall be interpreted as the grade shown on the drawings within a tolerance of + 40 mm.

5.5.4    Excavation and general grading to design elevation shall be completed prior to excavation for foundations and trenches for underground piping and utilities.

5.5.5    Earthwork construction shall not be carried out when the air temperature is below -5°C or during periods of rain or other unsuitable conditions.

 

5.5.6    Surplus materials resulting from excavation shall be deposited as fill in designated areas or transported to designated spoil areas as directed by COMPANY.

5.5.7    Borrow pit areas, if needed, shall be cleared and grubbed in accordance with this specification and the top soil stripped and stockpiled for future reclamation.

 

a.       The sides of the borrow pit shall be excavated to a slope of 3:1 and the excavation shall be carried out in such a way as to avoid ponding of water in the excavation.

 

b.       After completion of the borrow operation, CONTRACTOR shall spread the stockpile fill evenly over the entire pit area. The areas shall be left in a neat and tidy condition to the satisfaction of COMPANY and the land Company upon whose land the pit is located.

 

5.5.8    Authorized over-excavation is defined as that additional excavation required by COMPANY as a result of unsuitable natural soils conditions. Replacement fill shall be placed and compacted in accordance with this specification.

 

5.5.9    Unauthorized over-excavation is defined as that additional excavation required by COMPANY which is necessitated by the result of the CONTRACTOR'S operation or over-excavation by CONTRACTOR'S error. Replacement fill shall be placed and compacted in accordance with this specification, but at no additional cost to COMPANY.

 

5.5.10 The CONTRACTOR shall have full responsibility for the stability of excavation and safety of workmen. If any slip occurs, the CONTRACTOR shall remove all the slipped material from the excavated area/pit, at his own expense. Also, if any damage to adjacent above or underground structure occurs because of the slip, the CONTRACTOR shall repair or replace such structure to the satisfaction of the company at the CONTRACTOR’s expense.

 

5.5.11 Temporary unshared slope shall be 1(V) to 2 (H) for maximum depth of excavation of 2 meters unless noted otherwise on drawings.

5.5.12 Maximum permanent unsored slope shall be 1(V) to 3 (H) unless noted otherwise on drawings or approved by the COMPANY in writing.

5.6    Excavation in Hard Rock

 

5.6.1    In case where excavation, both in ordinary soil and hard rock, are involved, the ordinary soil comprising of soft, hard and dense soils and weathered disintegrated rocks which can be excavated without blasting, shall be completely stripped off and the starting levels of hard rock surface taken to enable measurements. Further work in hard rock shall be resumed after clearance from the COMPANY.

 

5.6.2    Personnel deployed for rock excavations shall be protected from all hazards such as loose rock/boulder rolling down and from general slips of excavated surfaces. Where the excavated surface is such that it is not stable against sliding, necessary supports, props, bracing or bulkheads shall be provided and maintained during the period of construction.

 

5.6.3    In case where blasting is prohibited for some reason, though otherwise required, the excavation shall be carried out by chiselling, wedging or any other approved method.

 

5.6.4    In trenches, pits and drains where blasting is not prohibited, the excavation in hard rock shall be carried out by blasting in the first instance and finally by chiselling so as to obtain the correct section of the trench as per drawing.

5.6.5    All hard boulders encountered shall be kept on site for later used as rip-rap material.

 

5.7    Stripping Bluffs and Loose Rock

 

5.7.1    All loose boulders, semi-detached rocks not directly in the excavation but so close to the area to be excavated which in the opinion of the COMPANY could endanger the workmen, equipment, or the work shall be stripped off and removed away from the areas of the excavation.

 

5.7.2    Any material not requiring removal as contemplated in the work, but which in the opinion of the COMPANY, is likely to become loose or unstable later, shall also be promptly and satisfactorily removed as directed by the COMPANY.

5.8    Subgrade Preparation

 

5.8.1    Prior to placing fill, all areas receiving fill material shall be prepared as follows:

 

a.       Remove vegetation, debris, unsatisfactory soil materials, obstructions, and deleterious matter from ground surface prior to placement of fills.

 

b.       Where subsoil is poorly graded and “wave” formation occurs during compaction, the outer limits of area to be compacted shall be extended at least 1 meter beyond the outer edges. On completion of compaction, the exact area shall be demarcated and extra area near the edge shall be scarified (It is assumed that the area near the edge is unconfined state and hence not properly compacted). This will ensure that the resulting area is properly compacted.

 

c.       Where fill is to be placed on original hillsides or existing embankments with a side slope greater than 5 horizontal to 1 vertical, the existing slope shall have benches excavated to key in the fill; the benches shall be cut to a minimum width of 3000 mm and constructed such that a slip plane does not develop between the existing material and the new fill material.

 

d.       The dry density against moisture content plot and values of dry density optimum moisture content obtained in accordance with IS 2720 (P 8) using compaction method.

5.8.2    Proof rolling shall be the method of detecting soft spots.

 

5.8.3    Proof rolling shall be carried out in the presence of qualified geotechnical personnel. The exposed subgrade should be proof-rolled, where feasible, with a heavy (90KN) vibratory roller to exposed loose or weak zones.

 

5.8.4    The areas to be proof rolled shall receive at least three complete passes. Consecutive passes shall be made perpendicular to each other.

5.8.5    Any areas of soft, rutted or displaced materials detected during proof rolling shall be examined and either re-compacted or the existing material removed and replaced with new fill material compacted to the specified density.

5.9    Placement and Compaction of Fill

 

Tolerance as per code. Minimum information as below:

 

Bank Grading + 50mm from true levels

 

Embankments + 75 - 0 from true levels

 

 

5.9.1    Excavated material suitable for use in a particular section of the work as fill or backfill shall be selected, loaded, hauled, placed spread and used to construct the fill or backfill to the lines and grades specified for the work.

5.9.2    Fill material shall be placed in 15 to 20 cm thick loose lifts and compacted to at least 95 percent of the maximum dry density as determined by ASTM D698 (Standard Proctor) unless noted otherwise on drawings.

 

5.9.3    Clods or lumps shall be broken up and mixed by blading, harrowing or similar method until a layer of uniform density is obtained. Each layer of material shall be uniform as to material, density and moisture content before beginning compaction. Fill material containing excessive or insufficient moisture shall be brought to the proper moisture content prior to rolling to achieve the specified compacted density.

 

5.9.4    Compaction shall be carried out using equipment specifically designed for compaction purposes.

 

5.9.5    Only hand held compaction equipment shall be used in the compaction of fill within 500 mm of retaining walls.

5.9.6    Take care to prevent wedging action of backfill against structures by carrying the material uniformly around the structure to approximately the same elevation in each lift.

 

5.9.7    Where the construction includes basement or other underground walls with structural floors above, do not backfill such walls until the structural floors are in place and have attained sufficient strength to support the walls.

 

5.9.8    Do not place backfill against retaining walls until the concrete has attained sufficient strength as determined by compressive strength tests.

5.9.9    Field density test shall be done as per code. The requirement of field tests to suit subgrade condition shall be determined by field engineer.

5.10 Tank Bases, Dikes and Road Subgrades

 

5.10.1 Tank bases, dikes and road subgrades shall conform to the dimensions and elevations shown on the drawings.

5.10.2 Materials used for tank bases, dikes and road subgrades shall be onsite excavated sand or crushed stone and the compaction of this material shall be in accordance with this specification.

 

5.10.3 The bottom of excavations shall be kept dry and free of loose material or debris. Backfill material shall be placed on sound, natural undisturbed soil.

5.10.4 All rocks that protrude above the final subgrade shall be removed.

 

5.10.5 Ponding of water in the excavation area or in the fill shall not be permitted. All materials disturbed by ponded water shall be removed and replaced with compacted granular fill.

5.11 Excavation and Backfill for Trenches

 

5.11.1 Trenches shall be excavated so that the piping or other facilities can be laid to the alignment and depth shown on the drawings.

5.11.2 Trenches shall be of sufficient width to allow satisfactory jointing of pipe and tamping of backfill under and around the pipe.

 

5.11.3 Trench walls shall be vertical, where possible, from the bottom of the trench to at least 100 mm above the top of the pipe and be smooth and free of projecting stones and boulders. All trenching shall meet applicable safety regulations.

 

5.11.4 Adequate measures shall be taken to prevent slips, cave-ins and slides. Tunnelling shall not be allowed unless accepted in writing by COMPANY.

5.11.5 The trench bottom shall be firm and fully capable of supporting the pipe to be installed. Where unstable material such as muck or peat is encountered, the trench bottom shall be over excavated to a depth

which stable material is encountered and the over-excavation shall be backfilled with gravel or other suitable material, compacted in lifts not exceeding 200 mm and compacted to 95 percent maximum dry density as determined by ASTM D698, or approval equal?

 

5.11.6 Where rock, hardpan or other unyielding material is encountered, the bottom of the trench shall be over-excavated to a distance below the pipe of one fourth of the pipe diameter but not less than 200 mm. The over-excavation shall be centered about the pipe, be 300 mm wider than the pipe outside diameter and be backfilled with a granular select fill compacted to 95 percent maximum dry density as determined by ASTM D698, or approval equal.

5.11.7 The bottom of excavations shall be kept dry and free of loose material or debris. Backfill material shall be placed on sound, natural undisturbed soil.

5.11.8 Ponding of water in the excavation area or in the fill shall not be permitted. All materials disturbed by frost or ponded water shall be removed and replaced with compacted granular fill.

 

5.11.9 Trenches shall be backfilled immediately after the pipes have been laid and inspected, except that 24 hours shall be allowed for cement mortar joints to set before beginning backfill. All temporary blocking or supports shall be removed prior to backfilling above the bottom one-fourth of the pipe.

 

5.11.10Refilling of trench around pipe shall be with coarse sand or clean soil free from stones exceeding 5 mm in largest dimension, frozen lumps, chunks or highly plastic clay, or other deleterious materials.

5.11.11Fill material for the backfill above a plane 300 mm above the top of the pipe may contain gravel and stones under 150 mm diameter except as governed by other applicable sections of this or other specifications.

5.11.12Backfill material shall be placed equally along both sides of the pipe, in uniform layers not exceeding 150 mm loose depth, and compacted by hand, pneumatic tamper or other approved means, to a height equal to the top of the pipe. The remainder of the trench shall be backfilled and compacted to a density at least equal to that of the in situ material.

5.12 Timber shoring

 

5.12.1 Timber shoring shall be close or open type depending on the nature of soil and the depth of pit or trench. CONTRACTOR shall take all necessary steps to prevent the sides of trenches and pits from collapsing.

5.12.2 Closed Timbering

 

a.      'Closed' type timber shoring shall be as specified in IS: 3764 - Safety Code for Excavation work. Shoring required for deep excavations shall be designed by the CONTRACTOR and got approved by the COMPANY prior to its use in the work.

b.      The withdrawal of the timber shall be done very carefully to prevent the collapse of the pit or trench. It shall be started at one end and proceed systematically to the other end. No part of the work should be damaged during the removal of the timber.

 

c.      No claim will be entertained for any timber, which cannot be withdrawn and is lost or buried.

 

5.12.3 Open Timbering

a. In case of open timbering, the entire surface of the side of trench or pit is not required to be covered.

b. Vertical boards of minimum 250 mm x 40 mm sections shall be spaced sufficiently apart                                                                                                                 leave unsupported strips of maximum 500 mm average width.

 

 

 

c. The detailed arrangements, sizes of the timber and the spacing shall be subjected to the approval of the COMPANY. In all other aspects, specification for close timbering shall apply to open timbering also.

 

5.12.4 Left in timbering

 

If the COMPANY directs any timbering to be left in place for the safety of the structure or otherwise for reasons commensurate with the type of construction necessitating such decision, the CONTRACTOR shall be paid for at the scheduled item rate.

5.13 Disposal of surplus material

 

5.13.1 The CONTRACTOR shall dispose/haul the excavated materials and place in heaps, bunds, blankets, riprap with regular slopes as directed by the COMPANY.

6.0 FINISHED GRADING 6.1       Work Involved

Finished grading shall include the following work: excavation, fill, compaction, disposal of surplus material, borrowing of suitable material, placing of finished gravel, construction of sidewalks, landscaping and related survey work.

6.1.1    Grading

 

6.1.2    The material requirement shall be as shown on the drawings.

 

6.1.3    Finished grading shall conform to the elevations and grades shown on the drawings. Finished grade shall be interpreted as the grade shown on the drawings within a tolerance of + 25 mm.

6.1.4    Operating and building areas shall be properly graded so that they are free from low spots and that drainage will be carried away from these areas. Roads shall be suitably crowned and ditched to achieve adequate drainage.

 

6.2    Sidewalks

 

6.2.1    Where sidewalks are required, excavate 75 mm into the subgrade and place a 75 mm thick layer of 20 mm crushed stone.

7.0 SITE DRAINAGE

7.1    Drainage During Construction

 

7.1.1    During grading and excavating operations sufficient ditches and drains shall be placed to ensure adequate site drainage during construction in accordance with this specification.

 

7.2    Final Site Drainage

 

7.2.1    The final site drainage shall conform to the elevations, grades and details shown on the drawings.

7.2.2    Rip-rap shall be installed as shown on the drawings at confluence of main ditches, where lateral ditches enter main ditches above the invert of the main ditch and where turbulence is anticipated at the entrance and exits of culverts.

8.0 INSPECTION AND TESTING 8.1    General

8.1.1    CONTRACTOR shall provide access to the work at all times to COMPANY for checking materials, and fabrication and construction procedures.

8.1.2    COMPANY shall have the right to stop work and require repairs or alterations if, in his opinion, the materials or workmanship do not meet the required specification.

 

8.1.3    Any omissions or failure on the part of COMPANY to disapprove or reject any work or materials must not be construed as an acceptance of any defective work or materials.

8.1.4    CONTRACTOR will bear the cost of repair and additional inspection resulting from faulty material or workmanship.

 

 

 

8.2    Compaction Tests

 

8.2.1    The required tests and certification of compaction shall be made by an independent testing laboratory acceptable to the COMPANY.

8.2.2    Frequency of backfill material quality control:

 

a.     Sieve analysis, liquid and plastic limit tests and compaction tests to be conducted: one test at change of borrow area or every 100,000 m3.

 

b.       Field density: One test for every 400 m2 for each loose lift thickness.

 

c.       Backfill shall not be compacted with water on the surface.

 

d.       It is always ideal to prepare a test section to determine minimum number of passes of roller that will be required to achieve the proper compaction.

8.2.3    CONTRACTOR shall allot sufficient time between each lift for the testing to be carried out. If the material fails to meet the required density, the material shall be reworked or replaced and the construction method altered as necessary to obtain the required density.

9.0 MAINTENANCE

 

9.1.1    Protect newly graded areas from traffic and erosion, and keep free from trash and weeds. 9.1.2       Repair and re-establish grades in settled, eroded, and rutted areas to specified elevations.

9.1.3     Where subsequent construction operations or adverse weather disturb completed compacted areas, scarify the surface, reshape, and compact to the required density.